ERN1 and Hypercholesterolemia: In this study, we present evidence that ER stress and hypercholesterolemia in mice induces the phosphorylation of macrophage FMRP on S500 by the inositol‐requiring enzyme‐1 (IRE1), a conserved endoplasmic reticulum (ER) stress‐sensing kinase/endoribonuclease (RNase).